867. Transpose Matrix.md

867. Transpose Matrix

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leetcode-cn Daily Challenge on Febrary 25th, 2021.

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Difficulty : Easy

Related Topics : Array

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Given a 2D integer array matrix, return the transpose of matrix.

The transpose of a matrix is the matrix flipped over its main diagonal, switching the matrix's row and column indices.

Example 1:

Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
Output: [[1,4,7],[2,5,8],[3,6,9]]

Example 2:

Input: matrix = [[1,2,3],[4,5,6]]
Output: [[1,4],[2,5],[3,6]]

Constraints:

• m == matrix.length
• n == matrix[i].length
• 1 <= m, n <= 1000
• 1 <= m * n <= 10^5
• -10^9 <= matrix[i][j] <= 10^9

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Solution

• mine
  • Java
    • Runtime: 0 ms, faster than 100.00%, Memory Usage: 39.9 MB, less than 52.14% of Java online submissions

      // O(R * C)time
      // O(R * C)space
      public int[][] transpose(int[][] matrix) {
          int r = matrix.length;
          int c = matrix[0].length;
          int[][] res = new int[c][r];
          for(int i = 0; i < r; i++){
              for(int j = 0; j < c; j++){
                  res[j][i] = matrix[i][j];
              }
          }
          return res;
      }
      

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